This research program is designed to investigate biochemical patterns of prenatal maturation of the human lung surfactant system in high risk pregnancies and to clinically assess the predictive value of a newly developed enzyme linked immunosorbent assay (ELISA) for monitoring fetal and perinatal lung maturity. A major asjpect of the program is the investigation at the quantitative level of the temporal relationship of the apoproteins and phospholipid components of surfactant purified from amniotic fluid in normal and high risk pregnancies. Surfactant "apoproteins" in unfractionated amniotic fluids and pharyngeal and tracheal aspirates of newborns will be measure quantitatively using the ELISA. This data will be correlated with established biochemical tests of fetal lung maturity including lecithin to sphingomyelin ratio (L/S), phosphatidylglycerol (PG) to phosphatidylinositol (PI) ratio and levels of dipalmitoylphosphatidylcholine and PG. The values from ELISA, L/S, PG/PI and PG will also be correlated with factors which accelerate (glucocorticoid, premature rupture of membranes, hypertension) or delay (diabetes, male sex) lung maturatin, thereby affecting the incidence of hyaline membrane disease (HMD). The potential value of the ELISA as an additional clinical test for fetal lung maturity will be determined with special attention to samples with L/S ratios in the immature and transitional ranges, and in diabetic pregnancies where the L/S ratio is less reliable as a predictive test of fetal lung maturity. In addition, we will explore the possibility of using the ELISA as a biochemical marker of surfactant secretion during the exudative and proliferative (recovery) phases of HMD. Statistical design, analysis and modeling of actual data will involve parametric, nonparametric and time series methods.